Photoelectric measurement translating means



July 22, 1952 A. A. OBERMAIER 2,604,528

PHOTOELECTRIC MEASUREMENT TRANSLATING MEANS Filed Oct. 28, 1947 2SHEETS-SHEET 1 July 22, 1952 A A OBERMNER 2,604,528

PHOTOELECTRIC MEASUREMENT TRANSLATING MEANS Filed Oct. 28, 1947 2Sl-IEETS-Sl-IEET 2 HUP/ZO/VTAL VE'feT/CHL SWEEP a S11/EEP @MPL/F152'HMPL/F/ER asx@ @Ja/l /11/17 /1 0@ SPECTPOSCOPE yintensity over saidvarea.

y struction illustrated in-Figurel l;

' Patented July 22, 1952 rATENr oFricl-:1i

I PHOTOELECTRIC MEASUREMENT TRANSLATING MIEANS;

Alfred A. Ohermaier, Chicago, Ill., assigner to.. f Illinois TestingLaboratories, Inc., Chicago, Ill.,

a corporation of Illinois from a device accomplishing thesame Withoutplacing any additional loadon the device; to translate the measurementintona square Wave of current ci constant frequency with the breadth ofthe waves being a function of the quantity being measured; to integratethe energy of the square waves of current and thereby provide anindication 'of the quantity being measured or of the measurement made bythe device; to vtranslate a variable y'density' phenomenon into avariable amplitude` pattern for assisting in interpreting the formermandto apply to one set of deecting 'plates oicathode ray tube impulseswhich are a function yof the light from an area of variable lightintensity and 'to another set of its Adeiiecting"plates impulses of thesame frequency but of continuously varying magnitude for producing apattern on the' screen of the cathode ray tube whichorresponds to the-light Other objects oifiny' invention will, in part, be obvious and inpart appear hereinafter.

My invention is disclosed inthe embodiments thereof as shown intheaccompanying drawings and it comprises the .features of construction,combination -of elements and arrangement of parts whichwill-be'exemplified in the constructionshereinafter set,v forth and the scope ofthe application of which will be 'indicated in the appended claims.A` f

For a more complete understanding of the nature rand scope oflv my,invention reference can be had to theiollowing detailed description,taken together with the accompanying drawings, in

which:

Figure 1 illustrates, diagrammatically, the apparatus which can beemployed for translating a measurement of a varying quantity from adevice responsiveA to the sarhezto another measurement indicatingdevice;- Y I Figure 2 is a view,.in front elevationfof the discs andmasking plate employed in the con- Figure 3 illustrates,diagrammatically, certain of the circuits that. can 'be'employed forinterconnecting the light sensitive' device or photocell shown inlFigure 1 anda remotely located indicating instrument.;l n

Figures 4 andl 5 showisqua're waves oi the same Application october 2s,1947, serial Np. 782,504 z'olaims.' (c1. 177-351) frequency havingdifferent breadths correspondingv to different light intensitiesimpnging on the photocell; f' t Figure 6 illustrates, ldiagrammaticallyyhow several indications lcan be transmitted simultaneously over a singlecommunication channel using'the apparatus shown in Figures 1, Zand 3;

Figure 7 illustrates a modification of the system shown in Figure 1 for'use in conjunction with low impedance measuring circuits such as athermocouple; A

Figure S illustrates how my invention' can be employed yf or measuringchanges inthe height oi a column 0i? mercury in a manometer tube;

Figure 9 illustrates, diagrammatically, the apparatusthat may beemployed'for scanning an area of variable light intensity forreproducing the` same onfvthe'screen of a cathode ray tube;

Figure l0 is a view, in front elevation, of the disc and masking platesemployed in th'e'system shown'in Figure 9; Y

Figure -ll shows atypical image of the interfference fringes from aninterferometer or spec# troscope or the area of variable light intensityl'which is to be reproduced fon the screen of Vthe cathode ray tube; Y

Figure 12 illustrates the Wave form thatfis produced on the screen ofthe cathode ray tube by the variable Width slot in the disc shown inFigure 10; and Figure 13 illustrates atypical pattern shown on thescreen of the cathode ray tube corresponding to the area of variablelight intensity shown in Figure 11./

Referring now particularly to Figure 1 of the drawings, it will be`observed that reference character It designates the shaft of a measuringinstrument, such as an ammeter, volt meter, Watt meter or like measuringinstrument, having a pointer I l 'which is movable relative tothe scaleI2. It may be assumed 'that the vshaft I0 is rotated by a suitablemechanism through an extent which isa function of the quantity, i. e.,amperes, volts, watts, etc., being measured. The pointer Il and scalevl2 are shown in order to demonstrate more clearly one particularapplication of this invention. YIt: will be understoed, however, thatthey may be omitted and thai'I the shaft l0 may be rocked in response'toother varying quantitiesvsuch as steam pressures, speed, acceleration,etc. In accordance with this invention provision is made for translatingthe measurement provided by the movement of the shaft lll to a remoteposition without applying'any additional load to the shaft lil.'

Mounted on the shaft I for movement therewith is a disc I3 which, asshown in Figure 2, has an arcuate slot I4 therein of varying width. Itwillbe noted that the slot I4 varies from a minimum width atv one end I5to a maximum width at the otherend'IB. It will be understood that thedisc I3 is intended to rock only through 90 on correspondingl movementof the shaft I0 from the zero position to the position corresponding tothe maximum value of the quantity being measured. If the shaft I0 rocksthrough a shorter or longer arc to provide full scale deection, the slotI4 is correspondingly shortened or lengthened as will be understood.

The arcuate slot I 4 in the disc I3 registers with a rectangular slotI'I in a stationary masking plate I8 through which light raysconcentrated by a suitable lens I9 from a light source 20 pass. Therectangular slot I'I provides a light beam having a generallyrectangular cross section of l.

uniform intensity, rportions of which Vare permitted by the arcuate slotI4 to impinge on a cathode 2| of a light sensitive device or photocell22 having an anode 23. It will be understood that the amount of lightreceived by the photocell 22 will depend upon lthe extent that thevariable width slot I4 uncovers the rectangular slot I1 in the maskingplate I8. Thus the quantity of light impinging on the cathode 2| is afunction of the quantity being measured as determined by thedisplacement of the shaft I0 from the zero or initial position.

- It is possible to measure the Vvariation in light impinging' on thecathode 2| of the photocell 22 and thereby' to obtain an indicationcorrespending to the indication provided by the position of the shaftI0. However, such a system is subject to certain disadvantages which mayrender it ineffective and inaccurate. Certain of the sources of troublewith such a system reside in variations in the intensity of the lightrays emitted by the light source 20. Since the measurement providedbythe apparatus thus far described is a function of the light intensity,it is essential that the light emitted by the source be constant so thatvariations in the amount of ligh impinging on the cathode 2| will resultsolely from variation in the quantity being measured. Other difficultieslie in the fatigue of the photocell 22 and variations in the calibrationof Ythe amplifying means that is used in connection therewith.

With a view to overcoming the foregoing disadvantages in a system whichdepends solely for its accuracy on maintaining the foregoing factorsconstant, provision is made for converting the light rays impinging onthe cathode 2| into a series of impulses of fixed frequency and varyingwidth.- AFor this purpose a scanning disc 24 is provided having arcuatescanning slots 25 of uniform width, these slots being arranged, asshown, to scan the light beam transmitted through the rectangular slotI'I in the masking plate I 8 and so much of the same as passes throughthe arcuate slot I 4 in the disc I3. While four lscanning slots 25 areillustrated in the disc 24 it will be understood that a larger orsmaller number can be employed as desired.

The scanning disc 24 is mounted for rotation on a shaft 26 that may bedriven by any suitable means operating at a constant speed such as a.

motor 21 of the synchronous type that may be energized from a suitablesource 28 of alternating current such asa 60 cycle 110 volt source. YWhere the motor 21 is designed to rotate at a speed of 450 R. P. M. andfour scanning slots 25 are employed, the light beam directed through therectangular slot I'I and the arcuate slot I4 is scanned 30 timeseachsecond. Current impulses at this frequency iiow through thephotocell 22 and, as shown inzFigure 3, may be amplifled by a suitableYamplifier"3| and applied to a circuit indicated by the conductors 32.The ampliiier 3| may be of any suitable type, such as an electronicamplifier the details of construction of which are well known to thoseskilled in the art. The circuit represented by the conductors 32 may berelatively long in order to transmit the measurement of the quantity aspro-` vided bythe movement of the shaft I0 to a remote point. v

As shown in Figure 3 the conductors 32 are arranged to energize a highspeed relay or a trigger circuit employing electronic tubes as indicatedat V33". The high speed relay Aor triggerc'ircuit `33* may beconnectedto apply intermittently the voltage from acogistant voltagedirectour; rent sourcasuch as'a battery 34, to energize a meter-.35,such as a ballistic indicator, ffor integrating the; impulses thusapplied.

When the v.disc I3 occupies a position such that the.narrowend, I5 oftheslot I4 registers with the slot I1, thecu'rrent impulses through thephotocell 22 are in the form of rectangular waves 38 as shown inFigure-i. vIt will be noted that the breadth of these'waves isrelatively narrow, i. e., the time .that thecurrent is flowing isrelatively small as compared to the time that it does not flow. Whentheu arcuate slot I4 is shifted so that the other end I 6 uncovers themajor por.-v

tion of the .rectangular slotf I'I, Ythe current impulsesflowing.through-theA lphotocell`22 are as represented by the square wave39 shown `in Figure 5. In this case the breadth of each of the impulsesis relatively great or the time that each impulse ows is relatively longas compared to Vthe time that no current flows. The high speed relay ortrigger circuit 33 fol1ows thewave forms 38 or 39A or any intermediatewave form and effects corresponding energization of the meter 35. Sincethis meter is ofthe integrating ballistic type, its pointer 'assumes aposition which corresponds to the sum of the areas of each of theindividual square topped waves.l It follows, thereforathat the positionof the pointer of the meter 35, when the system isV properly calibrated,corresponds to the positionof'the shaft VI I).

It is possible lto transmit simultaneously several different indicationsover the signalling channel or circuit 32. 'I'his can be accomplished byseveral transmitters, as shown in Figure 6, which are duplicates of thetransmitter shown in Figure' 1 with the amplifier 3| of `Figure In eachtransmitter the scanning disc 24 is either rotated at a, different speedor a different number of slots 25 or both are used to providegdifferentfrequencies the breadth of each wave of which is controlled asdescribedas a function of the quantity being measured. Such transmittersare indicated at 4|, 42 and 43 in AFigure 6.

A selector switch 44 may be used to switch the -circuit 32 to theappropriate filter45, 46 or 4l for effecting corresponding operation ofa receiver 43 which includes essentially the relay .or trigger circuit33 of Figure 3 and the integrating meter 35. Of course it will beunderstood that the frequencies used are so chosen as to avoidinterference due to harmonics. Also,` instead of the communicationcircuit 32 being of a conduc- 52 haslight rays focusedthereon bycondenser lens I9 from a source 20. in a masking plate 53.servestoyprovidel ani-mage thatlfis `reflected by the mirror 52, afterthe beampasses through theobjectve lens 54, through the :scanning slotsin the scanningv discZQf-onto the cathode 2l of thephotocell ',,2.",A`asking plate 55 with a suitable lopening 'thereinf'iserves to preventextraneous light from impinging on the cathode 2|.

In Figure 8 there is illustrated a manometer tube 55 in which there islocated a mercury column 57. The position of the top of the column 51varies the Width of the light beam from the source impinging on thecathode 2l of the photocell 22. A masking plate 58 has an aperture whichdefines the maximum Width of the light beam from the source 2U. The disc24, rotated as described, scans the light beam thus provided for thepurpose described.

My invention also can be employed for translating a variable densityphenomenon to a variable amplitude pattern on the screen of a cathoderay tube for convenience in interpretation. In accordance With myinvention it is possible to do this and to provide a pattern whichfollows closely the changes in the area of Variable light 6d, the slotG3 being arranged to be scanned by an arcuate scanning slot 65 in a disc65. The disc 66 can be rotated by any suitable means such as synchronousmotor 6l that may be driven from a suitable source 68 of alternatingcurrent.l The source 58 may be a conventional 60 cycle.

llt volt source and the motor 61 can be arranged to drive the disc 6G atany suitable speed such as a speed of 450 R. P. M.

The scanned light beam impinges on a multiplier phototube 1l Whoseoutput is amplified by a vertical sweep amplifier 12 and then applied tothe vertical deflection plates 13 of a cathode ray tube which isindicated, generally, at 14.

With a View to extending the pattern horizontally the disc 66 isprovided With an arcuate slot 15 of varying Width. It will be noted thatthe slot l5 extends from the end 16 of minimum width to the end 11 ofmaximum Width and that it extends through 180. When the disc 56 isrotated, the slot 15 moves relative to a slot 1S, Figure l0, in amasking plate 'i9v for the purpose of controlling the amount of lightWhich is emitted from a light source 8i) and directed by a suitable lensBI to the slot 18. The light which passes through the slot 15 falls on acathode 82 of a photocell, shown generally at 83, which has an anode 84.The output of the photocell 83 may be amplified by a horizontal sweepamplifier 85 and thereby applied to the horizontal deflection plates 86of the cathode ray tube 14.

The horizontal Apattern provided solely ,by the horizontal deflection.plates '86 'Whenflthey are energized as'described 4is illustrated at 31'inFigure 12. This saw tooth pattern' 81 appears horizontally across thescreenl 88.0ffthe cathode ray tube l. When light from thearea'of'variable light intensity, such as llustratedat inFig'-l ure 11,impinges on the multiplier phototube 7H vas'c'ontrolle'd by thescanningslot, andthe horizontal d'eilectionplates' areenergized asdescribed, the pattern as' illustrated .at 89, f'igV ure 13 appears onvthe-screen 88. The pattern 89. which appears on the screen 88 can ybe.interpreted much more readily than can the area of variable. lightintensity 60 providedas described.

Since certain changes can be ade in the foregoing constructions andsystems and different embodiments of the invention can be made Withoutdeparting from thefspirit and scope thereof, it is intended that allmatter shown in the accompanying drawings and described hereinbeforeshall be interpreted as illustrative and not in a limiting sense.

I claim as my invention:

l. Means for indicating the amount of angular movement of a first memberhaving turning movement, which comprises, in combination, means foremitting a light beam, photoelectric means for receiving the light beam,a masking plate having a rectangular slot traversed by the light beam,means connected to said rst member to turn in accordance with theturning movement of said first member and having an opening of acharacter to change the quantity of light transmitted through saidrectangular opening and impinging on said photoelectric means as afunction of the amount of turning movement of said first member,scanning means rotatable in a path intersecting that portion of thelight beam which traverses said rectangular opening and the opening of acharacter to change the quantity of the light transmitted through saidrectangular opening, whereby the photoelectric means is energized at afrequency determined by the speed of rotation of said scanning means andin amount determined by the quantity of light impinging thereon, thescanning means being in the form of a disc rotatable in the path of thelight and provided with a plurality of arcuate scanning slots of uniformwidth, and indicating means connected to said photoelectric means tointegrate the current impulses through said photoelectric means wherebyto indicate the amount of turning movement of said iii'st member.

2. Means for indicating the amount of angular movement of a first memberhaving turning movement, which comprises, in combination, means foremitting a light beam, photoelectric means for receiving the light beam,a kmasking plate having a rectangular slot traversed by the light beam,means connected to said first member to turn in accordance with theturning movement of said first member and having an opening of acharacter to change the quantity of light transmitted through saidrectangular opening and impinging on said photoelectric means as afunction of the amount of turning movement of said first member,scanning means rotatable in a path intersecting Athat portion of thelight beam Which traverses said rectangular opening and the opening of acharacter to change the quantity of the light transmitted through saidrectangular opening, whereby the photoelectric means is energized at afrequency determined by the speed Vrotatable in the path of the lightand provided with a plurality of arcuate scanning slots of uniformWidth,'and indicating means connected to said photoelectric means tointegrate the current impulses through said photoelectrc means wherebyto indicate the amount of turning movement of said first member. v

" ALFRED A. OBERMAIER.

REFERENCES CITED The following references are of record in the le ofthis patent:

UNITED STATES PATENTS Number Number Name l Date Young June 5, 1928 yOstrolenk Mar. 11, 1930 Baker Oct. 11, 1938 uRayner Oct. 17, 1939Eisle1' v July 16, 1940 Luck- V l Aug. 12, 1941 Snyder, Jr. Nov. 25,1947 FOREIGN PATENTS Country Date Great Britain Feb. 6, 1931

